D-ring substituted tetracyclines

ABSTRACT

The total synthesis of tetracycline-type antibiotics by a multistep process beginning with 3,4,10-trioxo-1,2,3,4,4a,9,9a, 10-octahydroanthracenes comprising: (1) an aldol condensation with a glyoxalic acid ester to give a 2-carboxymethylidene3,4,10-trioxo-1,2,3,4,4a,9,9a,10-octahydroanthracene ester; (2) Michael reaction of said ester with an amine to produce 3,4,10trioxo-1,2,3,4,4a,9,9a,10-octahydroanthracene-2-( Alpha amino)acetic acid ester; (3) conversion of the triketone to the corresponding 4,10-diketone by (a) selective reduction of the Michael reaction product to the corresponding 3-hydroxy compound, followed by conversion of the 3-hydroxy compound to the corresponding 3-formyloxy compound and removal of the 3-formyloxy group by treatment with zinc dust to give a 4,10-dioxo1,2,3,4,4a,9,9a,10-octahydroanthracene-2-( Alpha -amino)acetic acid ester; or (b) conversion of the hydrochloride salt of the Michael reaction product to a lactone by reaction with ptoluenesulfonic acid and treatment of the lactone with zinc dust formic acid; (4) conversion of the 4,10-diketo-1,2,3,4,4a,9,9a, 10-octahydroanthracene-2-( Alpha -amino)-acetic acid to a mixed anhydride; (5) followed by acylation of a malonic acid ester with the mixed anhydride; (6) cyclization of the acyl malonate derivative to a 12a-deoxytetracycline which is then hydroxylated to a tetracycline. The preparation of the 3,4,10-trioxo1,2,3,4,4a,9,9a,10-octahydroanthracenes from benzoyl halides by (a) Friedel-Crafts reaction of a benzoyl halide with a pyrocatechol ether, e.g., a di-(lower)alkyl ether, to produce a 3,4-di-(lower)alkoxybenzophenone; (b) conversion of the benzophenone by partial or complete reduction of the carbonyl group by chemical or catalytic methods to a 3,4-di-(lower)alkoxy diphenyl methanol or 3,4-di-(lower)alkoxy diphenyl methane; or to a 3,4-di-(lower)alkoxy diphenyl alkane via a Grignard reaction and reduction of the thus-produced alkanol; (c) oxidation of the 3,4-di-(lower)alkoxy diphenyl alkane, or the corresponding dihydroxy compound, to a dienedioic acid ester or dienedioic acid; (d) hydrogenation of the dienedioic acid compound to a benzyl adipic acid derivative; (e) cyclization of said compound to a 2-(2-carbalkoxyethyl)-4-tetralone by means of dehydrating or dehydrohalogenating agents; (f) cyclization of the 4-tetralone derivatives by condensation with a dialkyloxalate to give a 2carbalkoxy 3,4,10-trioxo-octahydroanthracene; and (g) removal of the 2-substituent by decarboxylation. The intermediates and final products are useful as bactericides and/or chelating agents.

United States Patent [191 Conover et al.

[ 1 Jan. 21, 1975 D-RING SUBSTITUTED TETRACYCLINES [75] Inventors: LloydH. Conover, Quaker Hill,

Conn; Robert B. Woodward, Belmont, Mass.

[73] Assignee: Pfizer Inc., New York, NY.

[22] Filed: Jan. 7, 1971 [21] Appl. No.: 104,747

Related US. Application Data [63] Continuation-in-part of Ser. No.647,238, June 19, 1967, abandoned, which is a continuation-in-part ofSer. No. 209,269, July 11, 1962, abandoned, which is acontinuation-in-part of Ser, No. 132,304, Aug. 18, 1961, abandoned.

[52] U.S. Cl..... 260/559 AT, 260/239.3 T, 260/520, 260/243 B, 260/544M, 260/247.1, 260/562 R, 260/247.2 A, 260/571, 260/247.2 B,

PC, 260/612 D, 260/268 TR, 260/613 D, 260/293.56, 260/623 D, 260/326.33,

[56] References Cited UNITED STATES PATENTS 3,029,284 4/1962 Gordon260/559 AT 3,188,348 6/1965 Butler et a1 260/559 AT 3,338,963 8/1967Petisi et al 260/559 AT R26,253 8/1967 Petisi et a] 260/559 AT PrimaryExaminerDonald G. Daus Assistant Examiner-Anne Marie T. Tighe Attorney,Agent, or Firm-Connolly And Hutz [57] ABSTRACT The total synthesis oftetracycline-type antibiotics by a multistep process beginning with3,4,10-trioxo- 1,2,3 ,4,4a,9,9a, 1 O-octahydroanthracenes comprising:

(1) an aldol condensation with a glyoxalic acid ester to give a2-carboxymethylidene-3,4,l0-trioxo-1,2,3,4,4a,9,9a,10-0ctahydroanthracene ester; (2) Michael reaction ofsaid ester with an amine to produce3,4,10-trioxo-1,2,3,4,4a,9,9a,lO-octahydroanthracene- 2-(a-amino)aceticacid ester; (3) conversion of the triketone to the corresponding4,10-diketone by (a) selective reduction of the Michael reaction productto the corresponding 3-hydroxy compound, followed by conversion of the3-hydroxy compound to the corresponding 3-formyloxy compound and removalof thc 3-formyloxy group by treatment with zinc dust to give a4,10-dioxo-1,2,3,4,4a,9,9a,10-octahydroanthracene- 2-(a-amino)aceticacid ester; or (b) conversion of the hydrochloride salt of the Michaelreaction product to a lactone by reaction with p-toluenesulfonic acidand treatment of the lactone with zinc dust formic acid; (4) conversionof the 4,10-diketo-1,2,3,4,4a,9,9a,10-octahydroanthracene2-(a-amino)acetic acid to a mixed anhydride; (5)followed by acylation of a malonic acid ester with the mixed anhydride;(6) cyclization of the acyl malonate derivative to a12a-deoxytetracycline which is then hydroxylated to a tetracycline. Thepreparation of the 3 ,4, l 0-trioxo-1,2,3,4,4a,9,9a,l0-octahydroanthracenes from benzoyl halides by (a)Friedel-Crafts reaction ofa benzoyl halide with a pyrocatechoi ether,e.g., a di- (lower)alkyl ether, to produce a3,4-di-(lower)alkoxybenzophenone; (b) conversion of the benzophenone bypartial or complete reduction of the carbonyl group by chemical orcatalytic methods to a 3,4-di- (lower)alkoxy diphenyl methanol or3,4-di- (lower)alkoxy diphenyl methane; or to a 3,4-di- (lower)alkoxydiphenyl alkane via a Grignard reaction and reduction of thethus-produced alkanol; (c) oxidation of the 3,4-di-(lower)alkoxydiphenyl alkane, or the corresponding dihydroxy compound, to adienedioic acid ester or dienedioic acid; (d) hydrogenation of thedienedioic acid compound to a benzyl adipic acid derivative; (e)cyclization of said compound to a 2-(2- carbalkoxyethyl)-4-tetralone bymeans of dehydrating or dehydrohalogenating agents; (f) cyclization ofthe 4-tetralone derivatives by condensation with a dialkyloxalate togive a 2-carbalkoxy 3,4,l0-trioxooctahydroanthracene; and (g) removal ofthe 2- substituent by decarboxylation. The intermediates and finalproducts are useful as bactericides and/or chelating agents.

6 Claims, No Drawings D-RING SUBSTITUTED TETRACYCLINES CROSS-REFERENCESTO RELATED APPLICATIONS This application is a continuation-in-part ofcopending application Ser. No. 647,238, filed June 19, I967, and nowabandoned which is in turn a continuation-inpart of copendingapplication Ser. No. 209,269, filed July I1, 1962, and now abandonedwhich in turn is a continuation-in-part of application Ser. No. 132,304,filed Aug. 18, 1961, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a process ofpreparation of antibacterial agents. More particularly, it is concernedwith the discovery of new and novel synthetic routes for the preparationof known as well as new tetracycline products. It is also concerned withthe new and useful tetracycline products obtained thereby, as well aswith the new intermediates of the process.

The tetracycline antibiotics comprise a group of biologically activehydronaphthacene derivatives having the following essential structuralfeatures. The numbering system indicated is that employed by ChemicalAbstracts.

. CONT-I Among the biologically active members of this group are thosecontaining the following substituent groups:

as starting materials to produce both known and new tetracyclines havingthe formulae:

. A H 3 g on x i (XVII) wherein the various terms are as defined below,by the 5 reaction sequence illustrated in Flow Sheet I. It will beappreciated by those skilled in the art that several alternative routesexist for the conversion of compounds of formula I to the final productsof formulae XVI and XVII. The particular route adopted for thepreparation of a given tetracycline is largely dependent upon economicfactors, such as, availability of materials, and yields of reactionproducts throughout the sequence.

Further, the conditions for any reaction in the sequence can, unlessotherwise indicated, be varied Common Name Substituents tetracyclineS-oxytctrucyclinc 7-chlorotctrucyclinc o-tlcnxy-fi-oxytctrzicyclinc7-hromotetrucyclinc o-dumcthyltetracyclinc tetracycline SUMMARY OF THEINVENTION The present new processes utilize3,4,10-trioxol,2,3,4,4a,9,9a,l0-octahydroanthracenes (formula I) o'detxy-6-demethyltctrucyclinc fi-dcmethyl-7-chlorotctrucyclint:4-dcstlimethylaminotctrucyclinc 4-destlimcthylumino-i-chlorotctrucyclincx x x o o o l m 4-tlesdimethylumino-S-uxytutrzicyclinco-deoxy-6-dcmcthyl-4-dcsdimethylaminowithin the skill of the art. Theactual conditions employed are determined by the above listed factors aswell as by type and availability of equipment.

3 g; o X

In the compounds of this sequence, X and X,, the substituentscorresponding to the 7- and 8- position substituents, respectively, inthe final tetracyclines are selected from the group consisting ofhydrogen, trifluoromethyl, amino and substituted amino, lower alkyl,hydroxyl and lower alkoxyl;

X is OR wherein R is selected from the group consisting of hydrogen,lower alkyl, and benzyl;

A is selected from the group consisting of hydrogen, lower alkyl and BOCH(B wherein B is lower alkyl and B is selected from the groupconsisting of hydrogen and lower alkyl;

X is selected from the group consisting of hydrogen,

lower alkyl and benzyl;

R is selected from the group consisting of X and CO X (mixed anhydride)in which X is lower alkyl;

R and R when taken together with the nitrogen atom to which they areattached form a nitrogen heterocyclic ring selected from the groupconsisting of piperazino, morpholino, pyrrylo, pyrrolidino, 2-(lowercarbalkoxy)pyrrolidino and thiomorpholino;

R and R when taken separately are each selected from the groupconsisting of hydrogen, lower alkyl, alkanoyl containing 1 to 4 carbonatoms and B-dimethylaminoethyl;

with the proviso that only one of said R and R substituents is alkanoylcontaining 1 to 4 carbon atoms;

X is selected from the group consisting of cyano, and

0 l C-NHR in which R is selected from the group consisting of hydrogenand lower alkyl;

X is selected from the group consisting of CH CHOH,

XVI

XVII

ll -CH(OCH) and C==O;

Y is selected from the group consisting of hydrogen,

cyano and lower carbalkoxy.

It should be noted that although the X, X and X terms in the benzenoidmoiety of the above generic structures appear in the same sequence, theyneed not be present in this sequence in actual practice. Thisrepresentation is for convenience only and is not to be taken toindicate, for example, that X always represents the S-substituent, orthat X, represents the 6- or the 7-substituent. They can occur in anysequence in the benzoid moiety. It should be noted that the varioussubstituents in the final tetracyclines of formulae XVI and XVll or inthe intermediates for their production may be replaced by other groupsaccording to procedures described hereinafter. Thus, X, X and X may betransformed to hydroxy, hydroxyalkyl, nitro, cyano, carbalkoxy, alkylsulfonyl, halo sulfonyl, alkyl sulfinyl and sulfamyl. The A substituentmay be transformed to =CHB amino, monoor di-lower alkylamino and CH(B)OH wherein B is selected from the group consisting of hydrogen andalkyl, by appropriate reactions as is discussed below.

A wide variety of 4-aminotetracyclines are, of course, preparedaccording to the present processes by substituting various primary orsecondary alkyl, aralkyl or aryl amines for dimethylamine. Suitableamines include other dialkylamines, e.g., methyl, ethyl, propyl, etc.,amines; aralkyl and alkaryl amines, and N-alkyl derivatives thereof;e.g., N-methylaniline, benzylamine, heterocyclic amines, e.g.,pyrrolidine, morpholine, aminopyridines and N-alkyl derivatives thereof;arylamines, e.g., aniline and substituted derivatives thereof whereinthe substituent is hydroxy, carbalkoxy, nitro and amino; and ammonia.Further, hydroxyalkyl substituents on the nitrogen, where protected forsome of the reaction steps by ether formation or acylation, as discussedbelow, may be subsequently be regenerated, e.g., by HBr cleavage orhydrolysis.

Of the present new compounds of particular value are those containingthe following benzenoid moiety:

in which the preferred values of X are selected from the groupconsisting of 7-trifluoromethyl, 8- trifluoromethyl, 8-dimethylamino,7-lower alkyl, 8- lower alkyl, 7-hydroxyl, 8-hydroxyl, 7-lower alkoxyland 8-lower alkoxyl; and the preferred lO-position substituents (OR')are those wherein R is selected from the group consisting of hydrogen,benzyl and lower alkyl. These compounds are suitable for the preparationof biologically active tetracycline compounds not previously described.

DETAILED DESCRIPTION OF THE INVENTION From I to XVA is an aldolcondensation with a glyoxalic acid derivative, generally, a lower alkylester. The reaction is catalyzed by acids or metals, e.g., metal salts,preferably metal alkoxides. It is preferably conducted in an inertatmosphere, e.g., nitrogen, at a temperature of from about 80-120 C. forfrom to about 24 hours using from about Vs to 2.0 moles metal ion/- moleof triketone. The acid catalyzed condensation is conveniently carriedout in glacial acetic acid as solvent. Non-hydroxylic solvents such asbenzene, xylene, toluene, dioxane, dimethoxyethane,diethyleneglycoldimethylether and dimethylformamide are useful solventsfor the metal catalyzed condensation, especially when using metalalkoxides. Magnesium methoxide is especially useful in thiscondensation. Of course, when active hydrogen (in addition to that ofthe B-diketone system) is present, one extra equivalent of alkoxide isused per active hydrogen. The a-hydroxy ester, wherein the elements ofwater are added to the unsaturated ester, is also obtained in smallyield. Its production is favored by short reaction periods and lowtemperatures. Dehydrating agents, such as phosphorus oxychloride inpyridine at 0 C. and p-toluenesulfonic acid in benzene permitsdehydration and regeneration of the unsaturation.

The conversion of XVA and XV is a Michael reaction with an amine HNR RThe reaction is conducted at a temperature of from about 70 C. to about10 C. preferably at about 20 C. An excess of the amine is employed; asufficiently large excess frequently being used to serve both as solventand as reactant. A variety of other solvents can be used and areactually necessary when the amine is a solid at the temperature of thereaction. Such solvents include tetrahydrofuran, ethylene glycol ethers,diethyleneglycol ethers and chloroform. The only criteria essential forthe solvent are adequate solubility for the reactants, inertness and asufficiently low freezing point.

The reaction is run for periods of from 15 minutes to 24 hours dependingupon the reactants and temperature employed. Oxygen should be excludedduring the period when the product is in contact with the excess amine.The order of addition of the reactants appears, in general, to beimmaterial to the outcome of the reaction.

In some instances the ester group is transformed to the amidecorresponding to the amine reactant. Primary lower alkylamines may alsoenter into further reaction involving the 3-keto group. This appears tobe a transient or intermediate step in the reaction and, as long as theamine addition product is retained in solution, can be directly reducedto the 3-hydroxy amino acid ester (XVB). Isolation of the amine additionproduct, however, produces what is believed to be a fused lactampossibly via formation of a hydroxy amine at the 3-position followed byelimination of alcohol between the ester and amine groups.

From XV to XVB is a selective reduction with a suitable chemicalreducing agent, such as metal hydrides, especially sodium borohydride.The reaction is carried out by dissolving the amino acid ester reactantin a suitable reaction-inert solvent such as 12 dimethoxyethane,ethyleneglycol ethers, diethyleneglycol ethers and liquid amines. Whenhydroxylic solvents are employed, e.g. alcohols, an excess of sodiumborohydride is used. Reaction periods of from about 10 minutes to about3 hours are required. Of course, when active hydrogen is present in thereactants, one equivalent of sodium borohydride is required per activehydrogen in addition to that of the B-diketone system.

Alternatively, the reduction is conducted by adding the sodiumborohydride all at once to a vigorously stirred solution of the aminoacid ester (XV) in one of the aforementioned solvents at 70 C. followedby gradual increase in the temperature to 0 C. In this process, asabove, 0.5 to 4.0 moles of reducing agent per mole of amino acid esteris used. A ratio of l is, however, preferred (except in cases whereactive hydrogen is present).

From XVA to SVB is a selective reduction with a suitable chemicalreducing agent, such as sodium borohydride, of the Mannich reactionproduct X V. It is represented as a one-step conversion since theMichael reaction product need not be separated prior-to reduction.Simultaneous formation of the corresponding lactone also occurs.

The lactone, of course, serves as a suitable reactant for the productionof XVB by cleavage of the lactone ring under mild conditions.

The formation of XIX from XVIII (R =H) is accomplished by formation of amixed anhydride (R =CO X with a haloalkyl carbonate as described in theJ. Am. Chem. Soc. 75, 636-9 (1953) and the J. Org. Chem. 22, 248 (1957).Acylation of a malonic acid ester derivative, e.g. malonic diester,cyanoacetic ester, malonic ester half amide, including N-alkylatedamides and especially the magnesium salt of ethyl tbutyl malonamate,etc. with the mixed anhydride produces the corresponding malonic acidderivative. Reaction is conducted in a suitable solvent system such aschloroform, toluene, benzene, diethylether, acetonitrile,dimethylformamide, nitromethane, dioxane, tetrahydrofuran, ethers ofethyleneglycol and diethyleneglycol at from about 5 to about 35 C. forperiods ranging from 25 minutes to up to 3 days. When R is CO X themalonic acid derivative is employed as a magnesium enolate according tothe procedure of Tarbell and Price (J. Org. Chem., Loc. cit.)

Where X is N-alkyl, e.g. t-butyl, isopropylcarboxamido, treatment withconcentrated sulfuric acid yields the corresponding unsubstitutedcarboxamide.

The conversion of XIX to XVII is accomplished by standard basecatalyzedacylation using, for example, sodium alkoxides, sodamide or preferablysodium hydride. A ratio of at least 4 equivalents of base and desirablya great excess of up to equivalents is employed.

A variety of reaction-inert solvent can be used, e.g.

benzene, xylene, toluene, anisole, dimethylformamide. Dimethylformamidecontaining a small amount of methanol is the preferred solvent. Reactionis conducted under nitrogen at a temperature of from about 80 to about150 C., preferably 120 C., for periods of from about 3 minutes to up to24 hours depending upon the reactants. A period of 5 to 7 minutes isadequate, indeed preferred, in most instances. When Y CN, the 12-imidogroup which results is hydrolyzed with aqueous acid to the l2-ketogroup. Of course, when X, is lower carbalkoxy, the 2-cyano tetracycline(XVII) is obtained.

The compounds of structure XVI and XVII in which X, is a carboxamidegroup are biologically active tetracycline products, the latter beingl2a-deoxytetracyclines which are converted to tetracycline compounds XVIby introduction of a 12a-hydroxy group by known procedures such asdescribed in the J. Am. Chem. Soc., 81, 4748 (1959).

A preferred method of l2a-hydroxylation is the method described in U.S.Pat. No. 3,188,348, issued June 8, 1965 wherein is described thehydroxylation of certain metal chelates of the l2a-deoxytetracyclines.The advantage of this latter process lies in the fact that the hydroxygroup is introduced cisto the hydrogen at position 4a.

Compounds of structure XVI and XVII in which X, is carbalkoxy may beconverted to corresponding compounds in which X, is carboxamide byfusion with ammonium formate at elevated temperature followed byhydrolysis with dilute mineral acids. Such compounds may be converted tothose in which X, is carboxamide or CN by a variety of routes. Where theC substituent is H (X, H), treatment with an alkyl or acyl isocyanate inthe presence of sodium hydride or other base (triethylamine, alkalimetal alkoxides, sodamide, 1,4- diaza[2,2,2] bicyclooctane) introduces a2-N- substituted carboxamido group. In the case of an acyl isocyanate,the resulting 2-N-acyl carboxamide group is readily hydrolyzed to a2-carboxamido group by methanolic ammonia; while in the case of asecondary or tertiary alkyl isocyanate, e.g. t-butyl isocyanate, theresulting Z-N-alkyl carboxamido group is converted to the 2-carboxamidegroup by dealkylation with concentrated mineral acid and water. Thecarboxamido group may also be introduced into compounds XVI and XVII bytreatment with carbamyl chloride or an N-alkyl carbamyl chloride underbasic conditions, e.g. in the presence of triethylamine, or other baseas given above. Where a secondary or tertiary N-alkyl carbamyl chlorideis employed the resulting N-alkyl carboxamide is converted to anunsubstituted carboxamide by treatment with mineral acid as previouslydiscussed.

The reactions of isocyanates and carbamyl chlorides are generallycarried out at temperatures of from about 0 to about 70 C. Mostreactions proceed satisfactorily at room temperature after an initialcooling period which serves to moderate the reaction during the mixingof the reactants. Solvents such as dimethyl sulfoxide, toluene, dioxane,tetrahydrofuran, acetonitrile, ethers of ethyleneand diethyleneglycoland especially dimethylformamide are suitable for the reaction. Thereaction time varies from about 10 minutes to 24 hours depending uponthe reactants.

Additionally, the carboxamide group may be introduced at the 2-positionof these compounds by heating with urea under basic conditions. Forexample, the reaction may be carried out in dimethyl-formamide solutionunder the influence of triethanolamine at temperatures ranging from C.to the boiling point of the solvent. The reaction period varies with thestructure of the reactant. However, periods of from about 5 minutes toone hour are generally satisfactory.

In lieu of this procedure, fusion with urea at about 130 C. for from 15to 45 minutes under nitrogen serves to introduce a carboxamide group atC-2. (Scarborough, J. Org. Chem. 26, 3717 (1960)). Additionally,compounds in which hydrogen is at C-2may be treated with lower alkylhalocarbonates to introduce carbalkoxy under conditions similar to thosedescribed above for introducing the carboxamide group via carbamylchlorides. Further, ethyl ortho formate under acid conditions introducesa formyl group at C-2. The

aldehyde function thus produced can be subjected to typical carbonylreactions.

Compounds of structure XVII in which hydrogen is at G2 are converted tocorresponding compounds in which C-2 bears cyano by reaction with ethylchloroximinoacetate in the presence of an acid acceptor, e.g., sodiumcarbonate or triethylamine, followed by hydrolysis of the thus produced2,3-tetracycline-4',5'- isoxazole-3-carboxylic acid ethyl ester to thecorresponding 3'-carboxylic acid which is decarboxylated and convertedto the nitrile product by treatment with copper and ammonia. A furtherrelated method comprises the reaction of chlorine free cyanogen chloridewith compounds of structure XVII.

The diketo compound XVIII is obtained from the hydrochloride of XVB viathe lactone by treatment with from about 0.5 to about 2 equivalents ofp-toluenesulfonic acid in a suitable reaction-inert solvent (benzene,toluene, xylene) for periods of from about 5 hours to about 2 days. Atemperature of from about 80-140 C. is satisfactory. The lactonehydrochloride of XVB is then treated with zinc dust-formic acid for abrief period to give XVIII wherein X is hydrogen. A ratio of from 1 to20 equivalent of zinc dust is effective in cleaving the lactone to thefree acid; 6-7 equivalents are preferred. Formic acid is the solvent ofchoice. However, mixtures of formic acid-methanol-water or of aceticacidmethanol-water, in approximately l-l-l ratio, can also be used. Atemperature of about 25 C. is generally used, although this is not acritical level. To avoid reduction of the 4, 10-diketo system, itis-important that mild reaction conditions and brief contact times beemployed. Contact times of from about 30 seconds to several hoursdepending upon the reactants, are operative. In general, however,periods of from 45 seconds to seconds are favored.

Alternatively, conversion of XVB to the diketo compound XVIII (X =CH isaccomplished by reaction with acetoformic anhydride according to knownprocedures followed by removal of the 3-formyloxy group by one of thefollowing; treatment with zinc dustformic acid, or zinc dust in aqueousammonium hydroxide, calcium in liquid ammonia, or catalytichydrogenationPd-C) in tetrahydrofuran or formic acid. Care must be taken to avoidover reduction, that is reduction of the 4,10-keto group. For thisreason mild conditions are required. When using zinc dust formic acid,for example, reaction is effected at room temperature with contact timesof brief duration.

The 8-chloro atom of the diketo octahydroanthracene amino acid (XVIII, X=CII and R =H), corresponding to the 7-chloro atom of the finaltetracycline products can, if desired, be readily removed by catalytichydrogenolysis. Pd-C or Pt-C containing 5-10% of the metal are mosteffective for this purpose. Pd-C (l0%) is preferred. From about 0.1 to 1weight equivalent is used. Dimethylformamide, tetrahydrofuran, water,ethanol and ethylacetate, preferably ethanol, serve as solvents.Pressures of from about I atmosphere to high pressures, e.g. 70atmospheres or higher, and temperatures of from 20 C. to 60 C. or highercan be used. The preferred conditions are atmospheric pressure and roomtemperature for periods of about 3 hours. A base is required to take upthe hydrogen chloride produced. While a variety of bases, both organicand inorganic by nature, can be used, it is preferred to usetriethylamine, generally about 4 equivalents.

When the substituents of the present compounds are hydroxy or amino theuse of a blocking group is sometimes advantageous in obtaining highyields during their preparation. Especially useful blocking groups areacyl, benzyl, tetrahydropyranyl, methoxymethyl, methyl and ethylradicals. Benzyl ethers are particularly easily reduced to hydroxylgroups. Tetrahydropyranyl ethers are easily removed under mildly acidicconditions. Aeyl groups which may be used include the acetyl, propionyland butyryl, as well as the benzoyl, succinyl, phthaloyl, and the like.The lower alkyl blocking groups are preferred since these compounds arereadily preparable.

When desired the above mentioned blocking groups, i.e. enol etherradicals, may be removed. The enol radicals are hydrolyzed by treatmentwith aqueous acid as is well known by those skilled in the art. When theether radical is benzyl, hydrogenolysis over noble metal catalyst mayalso be used.

In compounds of formula XVII, for example, the compound wherein X, X,and A are hydrogen; X is methoxy; R and R are methyl and X isN-tbutylcarboxamido, the IO-methyl ether and the t-butyl group at the2-position are conveniently removed in a single step by treatment with48% HBr for up to minutes at about 100 C. If shorter periods of time,e.g. 5 minutes, are used only the 10 methyl ether may be cleaved.Alternatively, the protective methyl and tbutyl groups can be removed instep-wise fashion. Treatment with 85% H SO for 2 hours at about roomtemperature removes only the t-butyl group to give the lO-methyl etherof 6-demethyl-6,l2a -dideoxytetracycline. The lO-methyl group is thenremoved by treatment with 48% HBr, or with hot concentrated HCl, or hot50% H 50 The new compounds described herein are useful as chelating,complexing or sequestering agents. The complexes formed with polyvalentmetal ions are particularly stable and usually quite soluble in variousorganic solvents. These properties, of course, render them useful for avariety of purposes wherein metal ion contamination presents a problem;e.g. stabilizers in various organic systems, such as saturated andunsaturated lubricating oils and hydrocarbons, fatty acids and waxes,wherein transition metal ion contamination accelerates oxidativedeterioration and color formation, biological experimentation, metalextraction. They are further useful in analysis of polyvalent metal ionswhich may be complexed or extracted by these materials and as metalcarriers. Other uses common to sequestering agents are also apparent forthese compounds.

In addition, the compounds of Flow Sheet I are especially valuable asintermediates in chemical synthesis particularly in the synthesis of-deoxytetracycline, 6- deoxy-6-demethyltetracycline and other novelantimicrobial agents bearing structural similarities to the tetracyclineantibiotics. Many of the herein described compounds, especially thosecontaining one or more hydroxy groups in the benzenoid moiety, areuseful as antibacterial agents in their own right.

In the present new process, particularly as applied to the synthesis ofbiologically active tetracyclines, it is preferred to employintermediates in which the hydrogen atoms at the 9a and 2-positions ofthe anthracene ring (corresponding to the 4a and Sa-positions of thetetracycline nucleus) are in the cis arrangement. For example, preferredcompounds are depicted by the following formula (syn. compounds) A II inwhich G is a substituent other than hydrogen, as contrasted with anticompounds of the formula:

In general, syn and anti compounds are separable by virtue ofdifferences in physical properties, e.g. differences in solubility invarious solvents. Usually, fractional crystallization permits readyseparation.

It is a particular advantage of the novel triketo octahydroanthracenesof the present invention that, by virtue of the activating influence ofthe carbonyl oxygen, they equilibrate to the predominantly cisconfiguration in the course of preparation. This enables the synthesisto proceed in sterospecific fashion without the loss of material thatwould otherwise be entailed in the separation of syn and anti compounds.

However, since in the production of compounds of this type, the productmay consist of a mixture comprised of compounds differing in position 2of the anthracene nucleus, i.e. the hydrogen being both cis and trans tothe hydrogen at position 9a, the mixture can be converted to thepredominately cis arrangement by equilibration in aqueous alkali, e.g.by treatment with aqueous sodium hydroxide or under the influence of theamine in the Mannich reaction. The procedure merely involves dissolvingthe reaction product in aqueous base and allowing the mixture to standfor periods of several hours to ensure complete equilibration. In lieuof this procedure, equilibration is attained via the Michael reactionusing extended reaction periods.

It is recognized by those in the art that, when such compounds have anasymmetric center in the substituent G, they exist as diastereoisomerswhich, as previously mentioned, may be separated by fractionalcrystallization for each of the syn and anti compounds. Of course, as isknown, diastereoisomers are racemic modifications consisting of twostructures which are mirror images (optical antipodes). The racemicmodifications may be resolved according to standard procedures. In thepresent process it is preferred, however, to utilize thediastereoisomers of the syn compounds since changes in configuration mayoccur during the various procedural steps of the total synthesis totetracycline compounds, thus necessitating costly and timeconsumingresolution procedures. The syn diastereoisomers are converted totetracycline products which consist of the normal tetracyclines andtheir 4-epimers which are separable by known procedures. Of course, the4-epitetracyclines are useful in that they are converted to normaltetracyclines by known procedures.

The starting compounds of structure I are prepared according to thefollowing procedure:

III&

in the above formulae, X, X X and A are as previ- 65 ously describedwith the exception that substituent X L/a'here R 0;

is preferably not 2. nitro group since this group deactivates the ringof compounds of structure [I in the ring closure reaction to those ofstructure Ill; (R is lower alkyl or benzyl) and R is hydroxyl,benzyloxy, lower alkoxy or halogen (Cl, F, Br, or 1). Alternatively, thecorresponding nitriles (e.g. where COR is replaced by CN) may be used.Further, at least one of the two positions of the benzenoid ring orthoto the diester side chain must be available for the ring closure ofstructure 1] compounds. If desired, halogen, (Cl or Br) may beintroduced into compounds of structure I, ll, Ill and W in which atleast one of the benzenoid substituents is hydrogen by directhalogenation with a chlorinating or brominating agent by methodsgenerally employed for halogenation of an aromatic ring. In the case ofstructure III and IV compounds at least a 2-molar excess of halogenatingagent must be used since halogenation can also occur in the 2 andespecially 4a positions. A variety of such agents are known to those inthe art and include phosphorus pentachloride and pentabromide, sulfurylchloride, N-chloro or bromoalkanoamides, e.g. N-chlorandN-bromacetamide; N-chloro (or bromo) alkanedioic acid imides, e.g.N-halosuccinimide; N- halophthalimide; chlorine; bromine; N-haloacylanilides, e.g. N-bromoacetanilide, propionanilicle and the like;3-chloro-, 3-bromo, 3,5-dichloro and 3,5-dibromo-5,S-dimethylhydantoin;pyridinium perbromide and perchloride hydrohalides, e.g. pyridiniumperbromide hydrobromide; and lower alkyl hypochlorites, e.g. tertiarybutylhypochlorite.

0 III 1 where R =OR CO R Of particular value are compounds of thefollowing formula:

X A H l l l COR IID

through the represented by ll lll lV- I.

In the ring closure reaction of corresponding structure ll compounds, itis preferred that the benzenoid substituent (X para to substituent OR beother than hydrogen to enable the ring closure reaction to proceed inthe position ortho to substituent OR to afford corrsesponding structureIll compounds. If there is no substituent para to OR a halogen group maybe introduced by direct halogenation by conventional methods ashereinbefore described. The para halogen substituent may be removed, ifdesired, by hydrogenolysis, under the usual conditions, of the tetraloneresulting from the ring closure.

The ring closure of compounds 11 to III is accomsequences plished by anyof the commonly employed methods for such reactions which generallyinvolve the use of a dehydrating or dehydrohalogenating cyclizationagent. With compounds of structure II, a preferred method when R is OHor alkoxy, involves treatment of the starting compound with such ringclosure agents as hydrogen fluoride or polyphosphoric acid. When R inthe starting compound is hydroxy], it is usually preferred to usehydrogen fluoride; when R is lower alkoxy, polyphosphoric acid. When Ris halogen a Friedel-Crafts catalyst, of course, should be employed,e.g. aluminum chloride. m-Hydroxyor alkoxy-benzyl compounds of structurell having ON in place of COR lend themselves to the Hoesch synthesis(Berichte, 48, l 122 and 50, 462) wherein treatment with dry hydrogenchloride in the presence of zinc chloride leads to imine formation, andhydrolysis of the latter provides the tetralone keto group.

The condensation of compound III in which R is CR with oxalic ester aswell as ring closure of compounds Illa (after esterification of the freeacid with R,OH) are effected by the general methods for estercondensation reactions of this type. Usually the reaction is carried outin the presence of a strong base such as alkali metal, alkali metalalkoxides and hydrides, sodamide and the like. If the starting compoundin the oxalate condensation contains free hydroxyl, or amino groups itis preferred to block such groups by alkylation or acylation by knownprocedures. After the reaction is completed, the blocking groups may beremoved, if desired. The resulting product from structure Ill, ie thecorresponding 2-carbalkoxy or carbobenzyloxy compound of structure IV,on hydrolysis and decarboxylation yields compounds of structure I.Cleavage of the ether linkage or other blocking groups by any of thegeneral methods, e.g. treatment with mineral acid such as concentratedhydrobromic or hydriodic acid, or when R is benzyl, hydrogenolysis,gives free hydroxy groups in the benzenoid portion.

The starting compounds of the above described processes, i.e. compoundsof structure ii, are prepared by the following sequence of reactions.

x 7 2 OR OR ORI VII

OH 1X,

In the above sequence. R and R are lower alkyl or benzyl: and B ishydrogen or hydroxy.

The first of these reactions for the preparation of compounds ofstructure VII is by means of Friedel- Crafts reaction, e.g. AlCl incarbon disulfide. The conversion of compounds of structure VII to thoseof VIII in which A and B are hydrogen is by catalytic reduction, e.g.over copper chromium oxide or noble metal, e.g. palladium, catalyst atfrom atmosphere to superatmospheric pressures of hydrogen gas; where Ais alkyl and B hydroxyl, by reaction with a suitable Grignard reagent,e.g. AMgI-Ialogen; where A is alkyl or hydrogen and B is hydrogen, byreduction, i.e. hydrogenolysis, of corresponding compounds in which B ishydroxyl. From VIII to IX is a standard ether hydrolysis, e.g.concentrated hydrobromic acid.

From IX to X is an ozonolysis reaction giving rise to the dienedioicacid which on hydrogenation over a noble metal catalyst, e.g. palladium,palladium on carbon, platinum, platinum oxide, etc., gives compounds ofstructure II. In the ozonolysis reactions to form compounds of structureX it is not possible to employ as starting compounds those of structureIX in which there are adjacent hydroxyl groups in the benzene ringcontaining X, X and X as substituents, since such structures aresusceptible to the oxidation reaction.

Further, in the ozonolysis reaction compounds of structure IX in whichX, X and X are adjacent ether groups or adjacent ether and hydroxygroups cannot be used since they, too, are susceptible of oxidation. Theozonolysis reaction is applicable to compounds of structure VIII,subject of course to the above limitation, wherein OR represents anether group. In such cases the ester (X) is obtained. In thehydrogenation reaction, compounds of structure X may be used as the freeacids or corresponding benzyl or lower alkyl esters to providecorresponding products of structure II. Of course, benzyl esters mayundergo hydrogenolysis to the free acid.

In addition, appropriate methods are available for reduction of thebenzoyl keto group to a secondary alcohol. For example, Ila and VII canbe reduced with sodium borohydride, or by hydrogenation with palladiumcatalyst in non-acidic media. By other well-known replacement proceduressuch as the following, the secondary alcohol may be converted to areadily replaceable sulfonic ester group, e.g., the tosylate, mesulfate,etc., followed by reaction with an alkali metal cyanide, an amine, amalonic ester, or the like, thus affording means for introduction of acyano, amino or CH- (C 8 group in the 6-position of the finaltetracycline. The secondary alcohol can also be dehydrated and theresulting unsaturated compound reduced to the corresponding benzylderivative.

In this sequence of reactions, when X and/or X are halogen, care shouldbe taken to avoid prolonged hydrogenations which may result in theremoval of the halogen atom. The possibility of halogen removal may beminimized by the use of a lower alkanoic acid, e.g. acetic or propionicas solvent for the reaction. Of course, if removed, halogen may bereintroduced if desired by the method hereinbefore described.

In those compounds of structure IX in which there are adjacent hydroxygroups in the benzenoid moiety, such groups must be protected bysuitable blocking groups, e.g. etherified with lower alkyl or benzylgroups. Similarly, free amino groups may be acylated. Of course, theetherifying radical of the hydroxy group may differ from thatrepresented by R. If the etherifying radical is benzyl it maysubsequently be removed by hydrogenolysis. Alternatively, all ethergroups can be removed by hydrogen iodide treatment.

As will be appreciated from the preceding reaction sequence, it is mostconvenient to introduce the benzenoid substituents, X, X and X byemploying the appropriately substituted benzoic acid derivative asstarting material. Many of these benzoic acid derivatives arecommercially available, and others may be readily ob tained by thoseskilled in the art.

It will be noted that a number of the later steps of the precedingsequences involve reaction conditions which may affect certain of thesubstituent groups signified by X, X, and X For instance, in catalytichydrogenation; e.g. VII VIII, halo groups are subject to hydrogenolysis.Therefore, where halo groups are desired in the final product, these arebest introduced subsequent to the hydrogenation by an appropriatesubstitution reaction.

In commencing the sequence with a substituted benzoyl succinate, it isessential that an ortho ring position be unsubstituted, sincecyclization to form the center ring of the hydroanthracene occurs atthis position. For the preparation of the preferred compounds ofstructure I, which bear an OR substituent in the 5 position, theposition of the benzene ring between the OR group and the keto group inthe starting benzoyl succinate should be unsubstituted, to provide forthe subsequent ring closure. On the other hand, it is preferred to havea substituent in what corresponds to the 8-position of compound I,since, this precludes cyclization to that position in competition withthe desired cyclization [II III]. A CF alkyl, or acylamino group can beconveniently carried in this position from the outset. Alternatively, an8-substituent may be introduced during the reaction sequence, prior tothe cyclization. For example, compound II may be halogenated at thisposition, e.g. by treatment with chlorine in the presence of a catalyticamount of iodine or ferric chloride.

Compounds of structure II are also prepared by the following sequencesof reactions.

XIII

The conversion of compounds of formula XI to those of XII is aClaisen-type condensation of the lower alkyl ester of XI with succinicacid diesters to provide formula XII compounds. The conversion ofcompounds of formula XI to XIII is similarly a Claisen condensationusing acetic acid esters. The conversion of compounds of formula XIII toXII is by alkylation reaction with a monohaloacetic acid ester, and theconversion of XIV to Ila is such an alkylation followed by hydrolysisand decarboxylation. The preparation of compounds of formula XIV fromthose of formula XIII is by standard alkylation procedures preferablyusing H C Cl-ICO R or corresponding nitriles. This conversion may alsobe effected by alkylation with a B-halo acid derivative haIOgen-CI-I CIICO R or the corresponding nitrile. Each of these reactions are effectedunder standard conditions known to those skilled in the art, e.g. in areaction-inert solvent in the presence of a base such as Triton B(benzyltrimethylammonium hydroxide), sodamide, sodium hydride and theirobvious equivalents.

The conversion of compounds of formula XII to those of Ila is by knownstandard reactions, e.g. by reaction of formula XII compounds withcorresponding acrylic acid esters of the formula H C CHCO R in which Aand R are as previously described under the conditions of the Michaelreaction. It may also be effected by alkylation with B-halo-alkanoicacids of the formula Halogen-cl-l CH CO R or of the correspondingnitriles. Hydrolysis and decarboxylation of these compounds givesstructure Ila compounds. The conversion of structure Ila compounds tothose of structure II is brought about by reactions as previouslydescribed for preparing structure VIII compounds.

The present invention additionally is adaptable for the preparation ofother tetracycline molecules, as follows.

For compounds in which substituent X is nitro, the

XIV

tetralone of structure III is nitrated by standard procedures, e.g.,such as nitric-acetic anhydride acetic acid mixtures or nitric acidsulfuric acid mixtures. Those in which X is halogen, cyano, nitro orother such groups are prepared by a Sandmeyer reaction of thecorresponding diazonium salt with suitable salt reagents (Cu Cl Cu BrKI, etc.). The diazonium salt is obtained by diazotization of the aminocompound, prepared from compounds of structure II in which X is amino orproduced by the reduction of the corresponding nitro compound byconventional means, e.g., chemical means, such as, active metals (Sn)and mineral acids (HCI) or by catalytic hydrogenation, e.g., nickelcatalyst and superatmospheric pressure.

The amino group may also be introduced into the benzenoid ring bycoupling of aryldiazonium salts, e.g., benzene diazonium chloride or thediazonium salt of p-aminobenzenesulfonic acid, with compounds ofstructure II or III containing a free hydroxy substituent in the5-position of the 4-tetralone ring (3-position of the benzene ring)followed by reduction of the resulting phenylazo compound, e.g.,catalytic reduction over noble metal catalysts. An amino group may alsobe introduced in place of the keto carbonyl oxygen of compounds ofstructure VII and XIV by reduction of the corresponding oxime orhydrazone, by reductive ammonolysis of the keto carbonyl group overnoble metal catalysts or by reduction of the keto group to a secondaryhydroxy group by sodium borohydride followed by conversion to thetosylate and replacement of the tosylate group by an amino group.

A further modification of the present invention provides a means ofintroducing a variety of substituents in positions corresponding to the6-position of the tetracycline nucleus. This involves formation of thesecondary alcohol corresponding to structure IIA compounds representedby the formula:

co s

by partial reduction of the corresponding ketone over palladium catalystat superatmospheric pressure until only one molar equivalent of hydrogenis taken up. Compounds of structure llb are also intermediates for thepreparation of 6-demethyltetracyclines.

The benzoyl keto group of compounds of structure Ila may be subjected tothe Wittig reaction as described in Angewandte Chemie 71, 260-273 (1959)to produce the alkylidene derivatives lIc by treatment with the ylidprepared from a chloroether For introduction of aromatic nitro groups,the given compound, e.g. tetralone III, is nitrated by standardprocedures, such as treatment with nitric acid-acetic anhydride-aceticacid mixtures, or nitric-sulfuric acid mixtures. Those in which X ishalogen, cyano, halo sulfonyl nitro or other such groups may be preparedby Sandmeyer reaction of the corresponding diazonium salt with suitablesalt reagents (Cu Cl Cu Br etc.). The diazonium salt is obtained bydiazotization of the amino compound, which may in turn be prepared byreduction of the corresponding nitro compound by conventional means,e.g. chemical reduction with active metals (Sn) and mineral acids(l-ICl) or catalytic hydrogenation, e.g. with nickel catalyst atsuperatmospheric pressure. Aromatic cyano groups may be furtherconverted to carboxy or carbalkoxy groups where de- IIc sired bystandard hydrolysis and esterification.

of the formula (B )CHCIOB (where B is lower alkyl The amino group mayalso be introduced into the and B is hydrogen or lower alkyl.) Thenecessary benzenoid ring, e.g. in compounds of structure IIhavchloroethers are obtained by standard treatment of aling a phenolichydroxyl group, by coupling with my]- dehyde acetals of the formula (B)Cl-I(OB with an diazonium salts such as benzene diazonium chloride oracid Chloride g- Chem 231, 3 the diazonium salt ofp-aminobenzenesulfonic acid, fol- Treatment of compounds 11a in thisfashion with the ylid from chloromethyl ether, for example, converts theketo group to a methoxy-methylene group, which may be reduced tomethoxymethyl. The latter group may be carried through the subsequentsteps herein described to the 6-methoxymethyltetracycline. At this pointthe elements of methanol may be split out by standard procedures toobtain the 6-methylene-6-deoxy-6 demethyltetracycline.

The products of the above reaction may, inturn, be hydrogenated withnoble metal catalysts:

COzR

Subjecting the reduction products to the further synthetic sequencesillustrated herein yields tetracyclines having a 6-CH(B )OB substituent.Treatment of such tetracyclines with liquid hydrogen fluoride results inthe elimination of a mole of alcohol B Ol-l and provides tetracyclineshaving a CI-I(B at the 6-position. The latter treatment is, for example,conveniently effected 0 lowed by reduction of the resulting phenylazocompound, eg by catalytic hydrogenolysis with noble metal ctalysts.

As has been previously pointed out, normal discretion must be employedin subjecting certain of the sub- 5 stituted intermediates to the hereindescribed reaction steps. In the base condensation reactions, thepresence of a substituent having an active hydrogen (e.g. a hydroxyl, oramino group) will necessitate the use of an additional mole of thesodium hydride or other base.

The presence of more than one such substituent per so a,

molecule is preferably avoided in these reactions, e.g. by the use ofprotective ether groups as previously de- 0 scribed. The sameconsiderations apply to Grignard reactions and hydride reductions.l-lydroxyl groups can be subsequently regenerated from their ethers byconventional hydrolytic procedures such as treatment with hydrogenbromide. Similarly, protective benzyl ether after the introduction ofthe 12a-hydroxyl group. Altergroups can subsequently be hydrogenolyzedto obtain natively, treatment of such tetracyclines having a 6- hydroxylgroups where desired. CH(B )OB group converts this group to CH(B )Ol-IIn the reduction of benzoyl adipate Ila or benzophewith concurrenthydrolysis of any ether groups in the none VII to the correspondingbenzyl derivatives II and aromatic D-ring. VIII, chemical reduction withamalgamated zinc and The products of the Wittig reaction IIC may also beHCl by the well-known Clemmensen procedure may be hydrolyzed toaldehydes and the resulting aldehyde employed in place of catalytichydrogenolysis. Any group in turn converted by catalytic hydrogenationto ester groups which may be present in the molecule are a hydroxymethylgroup. The latter may be carried concurrently hydrolyzed in theClemmensen procethrough the subsequent reactions of synthetic sequencedure, and reesterification will therefore be necessary. with its freehydroxyl group, or preferably, in the form Alternative routes orprocedures can be used in place of a lower alkyl ether.

The described procedures are adaptable to the preparation of a varietyof tetracycline molecules, as follows:

of the Clemmensen reduction. Thus, in the reduction of benzoyl adipateIla to corresponding benzyl derivative II, the three-step procedurepreviously referred to is an appropriate alternative to directreduction, i.e. (l)

conversion of the keto group to hydroxyl, e.g. with sodium borohydrideor by mild reduction at room temperature with palladium on carbon inalcohol or other neutral solvent; (2) conversion of the resultingalcohol to the unsaturated compound by dehydration in anhydrous hydrogenfluoride; and (3) rapid hydrogenation of the resulting double bond, e.g.with palladium at room temperature and moderate hydrogen pressure, untilone mole of hydrogen has been consumed. An other alternative reductionprocedure which is suitable is the Wolf-Kishner reaction (Annalen, 394,90, 1912 and 1. Russ. Phys. Chem. Soc. 43, 582, 1911) wherein thebenzoyl derivative is converted to a hydrazone, and the latter is inturn reduced to the corresponding benzyl derivative by heating with abase such as sodium ethoxide.

The present invention provides a means of synthesizing tetracyclinecompounds including 8-substituted and other valuable new tetracyclines,not previously described, which are therapeutically useful by virtue oftheir antimicrobial activity.

Those skilled in the art will appreciate that the following examplesprovide a basis for preparing the listed tetracyclines and thecorresponding l2a-deoxy derivatives thereof.

Of particular significance in accordance with this invention are thosefinal tetracycline products (XVI and XVII) wherein a hydroxy group or agroup readily convertible to a hydroxy group (alkoxy or alkanoyloxy) ispresent at the 8-position. An additional substituent of importance inaccordance with this invention is the trifluoromethyl group when presentat the 7- and or 8- positions of the final tetracyclines.

TABLE I X on x 0 on o x 1 2 A 3 h B-NHZ H lO-OH H NMe comr 8-Me n lO-OHa NMe 001m s-un a 10-OH 11 M62 CONH2 a 7-Me lO-OH Me CH NMe comr H T Me10-011 Me NMe 30ml H T-Me lO-OH Me m com H H IO-OH H pyrrolidyl CONH2 Ha 10-0 a piperidyl contr a a 10-011 H morpholinyl C0NH2 8-0 a 10-01: HNMe com a T-Me 10-0 11 me 001m a it 10-01; Me Cl-l NMe com a a 10-05 Meim CONH2 n H 10-011 11 N112 00101 B-OMe n lO-OMe H NMe 001m H H lO-OMe11 N112 cornr H u lO-OMe a 1mm coma 8-OC H H 10-01! H NMe cotm 8-011T-Me lO-OH a NMe CONH2 H H lO-OH a us com! a 'r-mi 10-0H a NMe CONH2 a7-0014 10-0 11 NMe 001m 'I'ahlc l-(ontinued x 1 2 l 3% b a a 10-011 Me-NHCH2CH20H CONH2 a a lO-QH H -NHCK2CH2OH CONH2 a H lO-OH H-NHCH2CH2OCH3 001m a a lO-OH Bu NMe CONH2 a a 10-OH a NHMe comi H lO-OHH NHCH2CH 000011 cons n a 10-011 -NHCH CH NMe CONH2 a a 10-011 H-NHCH2CH2NHCH3 comr H H 10-0H H -NHCH CH N(C CONH2 n a 10-03 aN(CH3)CH2CH2OH comr a a 10-011 cn on NMe coim H a 10-01: H -N(CH NMeCHCH con-H a H 10-011 H -n on( m (0H CH 001m a a lO-OH H NMe momm H n -0HH NM -CONHMe Some of the new tetracyclines of the present invention arehomologs, isomers or closely related analogs of known tetracyclines.Many of the new tetracyclines are distinguished from prior art compoundsby their possession of important and desirable properties, such asextended in vitro and in vivo antibacterial spectra, activity againstorganisms which have inherent or acquired resistance to knownantibiotics, rapid absorption, sustained blood levels, freedom fromserum binding, preferential tissue distribution at various parts of thebody (e.g. kidney, lung, bladder, skin, etc.) which are sites forinfection, sustained stability in'a variety of dosage forms, resistanceto metabolic destruction, broad solubility, and freedom fromobjectionable acute and cumulative side-effects. The new tetracyclinesare useful in therapy, in agriculture, and in veterinary practiceboththerapeutically and as growth stimulants. in addition, they may beemployed as disinfectants and bacteriostatic agents, in industrialfermentations to prevent contamination by sensitive organisms, and intissue culture, e.g. for vaccine production.

The various new tetracyclines of the present invention which do notshare the antibacterial activity of the known tetracyclines are valuableintermediates in the preparation of other compounds of classes known tocontain biologically active members. Thus, the D-ring can be nitrateddirectly and the nitro derivatives reduced catalytically to anaminotetracycline. Further, the tetracycline products of this inventioncan be halogenated by known methods at the lla-, or in the case of a7-unsubstituted tetracycline, in the 7,1 la-positions by treatment withsuch halogenating agents as perchloryl fluoride, N-chlorsuccinimide,N-bromsuccinimide and iodobromide.

The present invention embraces all salts, including acid-addition andmetal salts, of the new antibiotics. Such salts are formed by well knownprocedures with both pharmaceutically acceptable and pharmaceuticallyunacceptable acids and metals. By pharmaceutically acceptable is meantthose salt-forming acids and metals which do not substantially increasethe toxicity of the antibiotic.

The pharmaceutically acceptable acid addition salts are of particularvalue in therapy. These include salts of mineral acids such ashydrochloric, hydriodic, hydrobromic, phosphoric, metaphosphoric, nitricand sulfuric acids, as well as salts of organic acids such as tartaric,acetic, citric, malic, benzoic, glycollic, gluconic, gulonic, succinic,arylsulfonic, e.g. p-toluenesulfonic acids, and the like. Thepharmaceutically unacceptable acid addition salts, while not useful fortherapy, are valuable for isolation and purification of the newsubstances. Further, they are useful for the preparation ofpharmaceutically acceptable salts/Of this group, the more common saltsinclude those formed with hydrofluoric and perchloric acids.Hydrofluoride salts are particularly useful for the preparation of thepharmaceutically acceptable salts, e.g. the hydrochlorides, by

solution in hydrochloric acid and crystallization of the hydrochloridesalt formed. The perchloric acid salts are useful for purification andcrystallization of the new products.

Whereas all metal salts may be prepared and are useful for variouspurposes, the pharmaceuticallyacceptable metal salts are particularlyvaluable because of their utility in therapy. Thepharmaceuticallyacceptable metals include more commonly sodium,potassium and alkaline earth metals of atomic number up to and including20, i.e., magnesium and calcium, and additionally, aluminum, zinc, ironand maganese, among others. Of course, the metal salts include complexsalts, i.e., metal chelates, which are well recognized in thetetracycline art. The pharmaceuticallyunacceptable metal salts embracemost commonly salts of lithium and of alkaline earth metals of atomicnumber greater than 20, i.e., barium and strontium, which are useful forisolating and purifying the compounds.

it will be obvious that, in addition to their value in therapy, thepharmaceutically-acceptable acid and metal salts are also useful inisolation and purification.

The new tricyclic intermediates of the present invention, in addition totheir value in synthesis, exhibit valuable antimicrobial activity. Theymay be employed as bacteriostatic agents, and are further useful inseparation and classification of organisms for medical and diagnosticpurposes. These new intermediates, by virtue of their B-diketonestructure, are also valuable chelating, complexing or sequesteringagents, and form particularly stable and soluble complexes withpolyvalent cations. They are, therefore, useful wherever removal of suchpolyvalent ions is desired, e.g., in biological experimentation and inanalytical procedures. Of course, as is well known to those skilled inthe art, such B-diketones may exist in one or more of several tautomericforms as a result of their ability to enolize. It is fully intended thatthe B-diketone structures herein employed embrace such tautomers.

The starting compounds of the present invention are readily preparableby known procedures. Many of these compounds, including both benzoicacid esters and benzophenone starting compounds, have been described inthe literature.

The following examples are given by way of illustration.

EXAMPLE I Monoethyl Ester of 3-(3-methoxybenzyl)Adipic Acid METHOD AFive grams of diethyl 3-(3-methoxybenzoyl)adipate and 2 g. of 5%palladium on carbon in 30 ml. of acetic acid are treated in aconventional Parr shaker at a pressure of 40 psi of hydrogen gas at 50C. until 2 moles of hydrogen are taken up. The first mole of gas istaken up rapidly and the second more slowly over a total reaction timeof up to about 30 hours. The mixture is filtered, concentrated underreduced pressure to an oil which is vacuum-distilled to obtain theproduct.

METHOD B The y-lactone of the enol form of the monoethyl ester of thestarting compound is hydrogenated over palladium on carbon by this samemethod to obtain this product, b.pt. 190-1 C. (0.3 mm.). Elementalanalysis gives the following results:

Calcd. for: C, H O C, 65.29; H, 7.53;

Found: C, 65.25; H, 7.68.

The corresponding diethyl ester is prepared by refluxing this product inethylene dichloride containing ethanol and sulfuric acid. The diester isobtained by diluting the reaction mixture with water, separating, dryingand concentrating the ethylene dichloride layer, and vacuum-distillingthe residual oil, m, 1.4973. Elemental analysis gives the followingresults:

Calcd. for: C H O C, 67.06; H, 8.13;

Found: C, 67.02; H, 8.31.

The starting compound together with the corresponding 'y-lactone areprepared by hydrolysis and decarboxylation of diethyl3-carbo-t.butoxy-3-(3 methoxybenzoyl)adipate (Example L) by refluxing indry xylene containing p-toluenesulfonic acid. The products are separatedby fractional distillation or may be used together as starting compoundfor this hydrogenation reaction.

EXAMPLE ll 3-(3-Methoxybenzyl)Adipic Acid METHOD A Amalgamated zinc isprepared by shaking for 5 minutes a mixture of 120 g. of mossy zinc, 12g. of mercuric chloride, 200 ml. of water and 5 ml. of concentrated HCl.in a round-bottomed flask. The solution is decanted and the followingreagents added: ml. of water and 175 ml. of conc. HCl, ml. of tolueneand 52 g. of 3-(3-methoxybenzoyl)adipic acid. The reaction mixture isvigorously boiled under reflux for 24 hours. Three 50 ml. portions ofconcentrated HCl are added at intervals of 6 hours during reflux.

After cooling to room temperature, the layers are separated, the aqueouslayer diluted with 200 ml. of water and extracted with ether. The etherextract is combined with the toluene layer, dried and concentrated underreduced pressure to obtain the product. METHOD B A solution of 6254.4grams (22.1 mole) 3-(3-methoxybenzoyl)-adipic acid in 38.5 liters ofglacial acetic acid is hydrogenated in a 15 gal. stirred autoclave inthe presence of 2.5 Kg 5 percent palladium-oncarbon catalyst at 1,000psig and 50C. until the theoretical amount of hydrogen has beenabsorbed. The catalyst is filtered off and the solvent removed from thefiltrate by distillation at reduced pressure. This gives 5,432 grams ofproduct in the form of an oil. It is further purified by conversion tothe dimethyl ester, fractional distillation, and hydrolysis, as follows:

A solution of 5,432 grams (20.4 mole) of the crude3-(3-methoxybenzyl)adipic adipic acid, 3,410 grams (106.6 mole)methanol, 10.6 liters ethylenedichloride and 106 ml. concentratedsulfuric acid is stirred and refluxed for 15 hours. The mixture iscooled and washed with water (3 X 5 l.), 5 percent aqueous sodiumhydroxide (l X 2 l.) and again with water (3 X 5 l.). Theethylenedichloride solution is dried over 3 lb. anhydrous magnesiumsulfate (with 2 lb. Darco G60 activated carbon). The drying agent andcarbon are filtered off and the filtrate concentrated at reducedpressure to remove solvent. The residue is distilled through a 3 X 16inch vacuum-jacketed fractionating column packed with porcelain saddles.After a forerun of 934.1 grams, the product is collected at 172.0C/0.2mm to 183C/0.35 mm. This amounts to 3076.6 g. of 95 percent pure ester.

The ester, 2943.4 grams (10.00 mole) is hydrolyzed by heating over asteam bath for 19 hours with 1 Kg. (25.0 mole) sodium hydroxide in 6liters of water. The hydrolysis mixture is acidified to pH ca. 1.0 byaddition of concentrated hydrochloric acid and the product is extractedinto methylene chloride (1 X 4 l. and 2 X 2 1.). The methylene chlorideextract is washed with water (1 X 4 l. 1 X 8 1.), dried over magnesiumsulfate, filtered and freed of solvent by distillation at reducedpressure. This gives 2,506 grams of 3-(3-methoxybenzyl)adipic acid inthe form of a very sticky oil.

METHOD C A solution of dimethyl 3-(3-methoxybenzyl)adipate (0.01 mole)in 280 ml. of 1:1 tetrahydrofuran: 1,2- dimethoxyethane at a temperatureof about -l0C. is treated with a solution of sodium borohydride (0.005mole) in 30 ml. of 1,2-dimethoxyethane and 10 ml. of water. After 15minutes, 5 ml. of glacial acetic acid is added and the mixture stirredfor 5 minutes. Hydrochloric acid (3 ml. of 6N) is then added, themixture stirred for an additional 0.5 hour, then poured into water. Theproduct, 3-[a-hydroxy-(3-methoxybenzyl)- ]adipic acid dimethyl ester, isrecovered by evaporation.

The hydroxy ester is placed in ml. of anhydrous hydrogen fluoride andallowed to stand overnight. The

hydrogen fluoride is then evaporated and the thus produced dimethyl3-(3-methoxy benzylidene)adipate dissolved in dioxane (300 ml. treatedwith 0.3 g. of palladium on charcoal and subjected to 50 psi at roomtemperature until an equimolar proportion of hydrogen is consumed. Themixture is filtered and the filtrate evaporated to dryness under reducedpressure to give the desired compound as the methyl ester. It ishydrolyzed to the acid by the procedure of Method B.

EXAMPLE lll Dimethyl 3-(2-chloro-5-methoxybenzyl)adipate METHOD A Amixture of 3.2 g. of dimethyl 3-(3-methoxybenzyl- )adipate and 1.4 g. ofNchlorosuccinimide in 30 ml. of trifluoracetic acid is stirred andheated on a steam bath for 30 minutes. The reaction mixture is thenpoured into 5% aqueous sodium bicarbonate with stirring, and the mixtureextracted with ether. The combined extracts are dried over anhydroussodium sulfate and then concentrated under reduced pressure to an oilwhich is vacuum-distilled to obtain the product, b.p. 200C.

(1.1 mm Hg).

METHOD C A solution of 1688 g. of 3-(3-methoxybenzyl)adipic acid and 50mg. of iodine in 9 liters of glacial acetic acid is stirred while asolution of 450 g. of chlorine in 8 liters of glacial acetic acid isadded during about 2 hours. The mixture is kept in the dark during theprocedure and the temperature maintained at 1015C. The

solvent is then removed by concentration under reduced pressure to give1,902 g. of a dark amber oil.

This procedure is repeated with ferric chloride in lieu of iodine withcomparable results.

METHOD D A mixture of 30.4 g. of diethyl 3-(3-methoxybenzyl- )adipateand 12.75 g. of sulfuryl chloride in 250 ml. of benzene is allowed tostand for 3 days at room temperature. At the end of this period, thereaction mixture is concentrated under reduced pressure to a gummyresidue which is vacuum-distilled to obtain the product.

METHOD E The procedure of Method B is repeated using as startingcompound the corresponding dicarboxylic acid to obtain3-(2-chloro-5-methoxybenzyl)adipic acid dichloride.

EXAMPLE IV Diethyl 3-(2-chloro-5-ethoxybenzyl)adipate This product isobtained by the procedure of Method A of Example lIl employing diethyl3-(3-ethoxybenzyl- )adipate in lieu of dimethyl3-(3-methoxybenzyl)adipate.

EXAMPLE v 2-(2-Carbethoxyethyl)-5-methoxy-8-chloro-4- tetralone METHOD AA mixture of 2 g. of diethyl-3-(2-chloro-5-methoxybenzyl)adipate(Example Ill) and 30 g. of polyphosphoric acid is heated on a steam bathfor 30 minutes and then poured into ice water. The oil then separatesand is collected.

METHOD B A mixture of 2.0 g. of the di-acid chloride of 3-(2-chloro-S-methoxybenzyl)-adipic acid in 30 ml. of carbon disulfide iscooled to 0C. and 4 g. of aluminum chloride added portionwise to thecooled mixture. The mixture is stirred for 30 minutes and then allowedto warm to room temperature where a vigorous reaction ensures. After thevigorous reaction subsides the mixture is warmed on a steam bath,cooled, diluted with water and the carbon disulfide steam distilled. Themixture is extracted with chloroform and the product obtained by dryingand concentrating the chloroform extract. The product is the free acidwhich, if desired, is converted to the desired lower alkyl ester byconventional methods. For example, the methyl ester is prepared asfollows: 7

A mixture of 2,002 g. (7.1 moles) of the tetralone acid, 3 L.chloroform, 682 g. (21.3 mole) methanol and 21.2 ml. conc. sulfuric acidis refluxed with stirring on a steam bath for 20 hours. The reactionmixture is then chilled and 2 L. each of chloroform and water are added.The organic phase is separated and washed successively with 2 X 2 L.water, 1 X 1 L. 2% aqueous sodium hydroxide and 3 X 4 L. water to afinal pH of about 7.5. After drying over anhydrous sodium sulfate andtreatment with Darco KB activated carbon the solution is filtered andconcentrated to a dark oil at reduced pressure. The oil is taken up in 6L. hot ethyl acetate and 11 L. hexane added. The solution is chilled to-5C. with stirring and 1,404 g. 2-( 2-carbomethoxyethyl)-5-methoxy-8-chloro-4-tetralone recovered byfiltration, hexane-washing and air-drying. The product melts at101.0102.4C.

EXAMPLE VI 2-(2-Carboxyethyl)-5-methoxy-8-chloro-4-tetralone Apolyethylene container is charged with 1,809 g. (6.03 mole)3-(2-chloro-5-methoxybenzyl)adipic acid and chilled in an ice bath while7 kg. liquid hydrogen fluoride is introduced from an inverted, chilledtank. The mixture is swirled to make homogeneous and then left toevaporate partially overnight in a hood. Most of the hydrogen fluoridethat remains is removed by placing the polyethylene container in warmwater to cause rapid evaporation. The remainder is removed by quenchingin about 10 L. water. The product is then extracted into chloroform,washed with water and dried over magnesium sulfate. Removal of thedrying agent by filtration and the solvent by distillation gives a gumthat is triturated with ether and filtered. This gives 1,031 g. of crudeproduct that is recrystallized from a mixture of 16 L. ethanol, 2 L.acetone and l L. ethylene dichloride, with activated carbon treatment.The first two crops amount to 863.9 grams. of white crystalline productmelting at [750 180.5C.

Elemental analysis gives the following results:

Calcd. for: C H, O Cl: C, 59.47; H, 5.35; CI, 12.54;

Found: C, 59.51; H, 5.42; Cl, 12.60.

Ultraviolet absorption shows A max at 223 mu 24,650), 255 mi (6 7,900)and 326 my. (6 4,510). Infrared absorption maxima appear at 5.76 and5.99 t.

This product is also obtained by hydrolysis of the product of Method A,Example V, by treatment with Hcl in acetic acid.

The methyl ester, ethyl ester (m. 575 9C.) and benzyl ester (m 84-85C.)are prepared by conventional methods.

3-(3-Methoxybenzyl)adipic acid, treated with HF as described, yields2-(2-carboxyethyl)-7-methoxy-4- tetralone, which melts at l58-9C. aftertwo recrystallizations from benzene-hexane and exhibits ultravioletabsorption maxima at 225 mp. (e 13,500) and 276 mp. (e 16,000) inmethanolic HCl and NaOH. Analy- SIS,

Calcd. for: C H O C, 67.73; H, 6.50%; Found: C, 67.67; H. 6.48%

EXAMPLE VII 2-( 2-Carboxyethyl )-6-chloro-7methoxy-4-tetralone Thissubstance is a byproduct of the cyclization of the products of ExampleIII. It is separated from the crude2-(2-carboxyethyl)-5-methoxy-8-chloro-4-tetralone of Example VI byvirtue of its chloroform insolubility. 2,900 g. of the crude tetraloneare leached six times with 8 liter portions of hot chloroform. 170 g. ofwhite solid remain, melting at 236-239C. Themethyl ester is prepared bythe procedure of Example V, Method B.

EXAMPLE VIII 2-( 2-Carbomethoxyethyl)-5-benzyIoxy-8-chloro-4 tetralone2-(2-Carboxyethyl)-5-methoxy-8-chloro-4-tetralone (25 g.), glacialacetic acid (200 ml.) and 48% hydrobromic acid (50 ml.) are heated at 90under nitrogen for 24 hours. The cooled solution deposits a crystallinesolid. The mixture is poured over two parts ice and the total solid cropisolated by filtration and thoroughly washed with water. The crude2-(2carboxyethyl)-5- hydroxy-B-chloro-4-tetralone obtained in this wayis recrystallized from acetonitrile to obtain 18.8 g. melting at 164-8C.

Elemental analysis,

Calcd. for: C H ClO C, 58.11; H, 4.88; CI, 13.20%;

Found: C, 57.99; H, 4.87; CI, 12.73%.

14.5 g. of this product is placed in 200 ml. dry methanol and themixture refluxed for 30 minutes as anhydrous HCl is passed through. Thenow clear yellow solution is allowed to stand overnight, and themethanol is then removed in vacuo. The residual gum is extractedexhaustively with hexane and the combined extracts are concentrated andcooled. HCl of the white, crystalline methyl ester separates and isfiltered off and recrystallized from hexane. The ester melts at68-69.5C. and analyzes as follows.

Calcd. for C H C1O C, 59.45; H, 5.35; CI, 12.6%;

Found: C, 59.16; H, 5.38;C1, 12.6%.

5.6 g. (0.02 mole) of this substance is dissolved in 500 m1. anhydrousmethanol and to this is added 0.02 mole sodium methoxide and 500 ml.benzene. The mixture is concentrated to dryness in vacuo at roomtemperature, then heated at C. and 0.1 mm for 10 minutes. The residue ismaintained under high vacuum at room temperature for 16 hours, and thedry solid added to 50 ml. benzyl bromide together with sufficientdemethyl formamide to solubilize. The mixture is heated at 100C. for 48hours with stirring, then cooled and filtered. The filtrate isconcentraed at reduced pressure and the residual oil chromatographed onacetonewashed and dried silicic in chloroform. The first effluentfraction consists of unchanged starting material. The main fraction,recognized by a negative ferric chloride test, deposits crystalline2-(2-carbomethoxy ethyl- )-5-benzyloxy-8-chloro-4-tetralone on standing.

EXAMPLE IX 2-Carbomethoxy-5-methoxy-8-chloro-3 ,4, 1 O-trioxo-1,2,3,4,4a,9,9a, IO-octahydroanthracene 30 Grams of2-(2-carbomethoxyethyl)-5-methoxy-8- chloro-4-tetralone (0.1 mole),prepared as described in Example V, Method B, is dissolved together with24 grams dimethloxalate (0.2 mole) by warming with ml. freshly distilleddimethyl formamide in a well dried two liter flask which has beenflushed with dry nitrogen. The solution is cooled to 20C. and to it isadded all at one time 0.4 mole sodium hydride in the form of a 50% oildispersion which has been exposed to the atmosphere for 24 hours inorder to produce a deactivating coating. The reaction mixture ismaintained at 20-25C. with an ice bath. 0.1 mole dry methanol is nowadded, and the temperature rises spontaneously to 4050C. When thetemperature begins to fall (about 5 minutes after addition of themethanol) the reaction vessel is removed from the ice bath and quicklyplaced in an oil bath at 110C. The reaction temperature is brought withdispatch to 90C. and maintained there for 10 minutes, or until activebubbling ceases if this occurs sooner.

The flask is now immediately transferred back to the ice bath, and whenthe temperature reaches 15C., 100 ml. of glacial acetic acid is added atsuch a rate that the temperature does not exceed 30C. At this point, ago]- den yellow precipitate appears. ml. methanol and 50 ml. water areadded and the mixture is digested at 45C. for 15 minutes and thenstirred in an ice bath for an hour. If only a scanty crop of crystals ispresent at this time the mixture may be stored in the refrigeratorovernight before proceeding. It is now transferred to a separatoryfunnel to permit separation of the oil from the sodium hydride oildispersion. The suspension is then filtered with suction, and the filtercake triturated three times with 100 ml. portions of hot hexane toextract impurities. The washed solid is next stirred with 200 ml. water,filtered, and then digested with 500 m1. refluxing methanol for 20minutes, to effect further purification. 15-l 6 grams of bright yellowneedles are obtained. The product melts at 200-205C. and exhibits nocarbonyl absorption below 6 p. In 0.01 N methanolic HCl it exhibitsultraviolet absorption maxima at 406 my. (6 14,200) and at 275-290 mp.(e 5,940). In 0.01 N methanolic NaOl-I it exhibits maxima at 423 my. (6=13,950) and at 340 my. (6 7.120).

EXAMPLE X 2-Carbomethoxy-6-chloro-7-methoxy-3 ,4, 1 O-trioxo- 1,2,3,4,4a,9,9a, l O-octahydroanthracene 2-( Z-carbomethoxyethyl)-6-chloro-7-methoxy-4- tetralone, prepared in Example VII, 30 g., isdissolved in 24 g. dimethyl oxalate in 300 ml. dry distilled dimethylformamide by warming. The solution is then cooled under nitrogen in anice-salt bath and 19.86 g. sodium hydride (51.2% in oil) added all atonce as the temperature is maintained below 20C. The ice bath is removedand the temperature rises spontaneously to 30C., whereupon the bath isreplaced briefly to control the vigorous reaction. The reaction mixtureis then heated to 7080C. for 5-8 minutes, cooled to below C., andtreated with 100 ml. acetic acid, added at such rate that thetemperature does not reach 25C. The reaction mixture is now poured intofour volumes of chloroform. The chloroform solution is washed withwater, then with saturated brine, and dried over anhydrous sodiumsulfate. The solvent is removed in vacuo, and the residue is treatedwith 350 ml. methanol. After standing for several hours at roomtemperature the slurry is filtered to obtain 12.5 g. yellow crystallineproduct, melting at 228231C. with decomposition and gas evolution.Recrystallization from chloroformmethanol raises the melting point to235.6236.8C. analysis,

Calcd. for: C H O CI: C, 58.21; H, 4.31; CI, 10.11%;

Found: C, 58.53; H, 4.43; Cl, 10.10%.

EXAMPLE XI 2-Carbobenzyloxy-5-methoxy-8-chloro-3,4,10-trioxo- 1,2,3,4,4a,9,9a, 1 O-octahydroanthracene 2-( 2-Carboxyethyl-methoxy-8-chloro-4-tetralone, 28.3 g. (0.10 mole), is combined with32.4 g. (0.30 mole) benzyl alcohol, 60 ml. ethylene dichloride and 0.6ml. conc. sulfuric acid. The mixture is heated at -reflux for 4 hours,then cooled and water-washed. It is then dried over magnesium sulfateand filtered. The filtrate is concentrated under reduced pressure andthe resulting 48 g. residue is crystallized from ethyl acetatehexane.25.7 g. of the benzyl ester of the starting compound is obtained,melting at 8185C. After recrystallization from ethyl acetate-hexane itmelts at 84.085.5. Analysis, calculated for C H 0 Cl: C, 67.65; H, 5.68;Cl, 9.51; found: C, 67.63; H, 5.81; Cl, 9.4.

The substance is dissolved together with 0.04 mole dibenzyl oxalate in50 ml. dry, distilled dimethyl formamide. To this is added 0.08 molesodium hydride in the form of a 50% oil dispersion, while maintainingthe temperature at about -25C. Benzyl alcohol, 0.02 mole, is added, andthe mixture is heated to 80C. for 5 minutes, then cooled to 20C. andslowly acidified with glacial acetic acid. The reaction mixture is nextevaporated to dryness under reduced pressure and the residue is taken upin chloroform. The chloroform solution is washed with water, then withbrine, dried over sodium sulfate, treated with activated carbon andfiltered. The filtrate is evaporated at reduced pressure to obtain thedesired product as residue. It is purified by evaporation of the highlyfluorescent, less polar eluate fraction from silicic acid chromatographyin chloroform.

EXAMPLE XIIZ-Carbomethoxy-S-Methoxy-8-chloro-3,4,10-trioxol,2,3,4,4a,9,9a,l0-octahydroanthraceneClean sodium metal (3.68 g.) is dissolved in methanol (50 ml.) and thesolution evaporated to a dry white solid in vacuo (this is mostsuccessfully carried out by using rotary vacuum equipment).Dimethyloxalate (9.44 g.) and benzene ml.) are then added to the flaskand refluxing is carried out for about 10 minutes under nitrogen (notall of the solids dissolve but the cake is broken up). The solution iscooled and dimethylformamide (50 ml.) then added followed by thedropwise addition of a solution of 2-(2-carboxyethyl)-5-methoxy-8-chloro-4-tetralone (Example VI) (11.3 g.) in dimethylformamide100 ml.) during one hour at 20 under N with stirring, and stirring atroom temperature under N is continued overnight. The solution is thenpoured into cold water 1 l.) and extracted twice with chloroform. Thechloroform extract is discarded and the aqueous solution acidified with10% HCl solution. The product is obtained by extraction with chloroform(3 X 200 ml.), backwashing once with water, drying over anhydrous NaSO.,, treatment with charcoal, filtration and evaporation of the solventin vacuo to give a red gum (16.4 g.) which is 2-(2-carboxyethyl)-3-methyloxalyl-5-methoxy-9-chloro-4-tetralone.

U.V. absorption maxima in 0.01 N NaOH at 258 and 363 mu. maximum in 0.01N CH1 at 347 mu, minimum at 277 mu.

The gum gives a deep red color with ferric chloride in methanol andliberates CO from a saturated NaHCO solution.

The acid is esterified by dissolving in chloroform (l 1.), methanol (50ml.) and conc. H 50 (10 ml.) and rfluxing gently for 15 hours. Thesolution is cooled, poured into excess water and the chloroform layerseparated. The aqueous layer is extracted with chloroform (250 ml.) andthe combined chloroform extracts are backwashed twice with cold water.The extract is then dried over anhydrous sodium sulphate, treated withactivated charcoal, filtered and evaporated to a red gum in vacuo. Thisgum does not liberate CO from saturated bicarbonate solution, and givesa deep red color with ferric chloride in methanl.

The ester product, 3.825 grams, and 1.275 g. of sodium hydride (56.5%solution in oil) are dissolved in 25 ml. of dimethylformamide. Anexothermic reaction sets in with the evolution of hydrogen gas. Afterthe evolution of gas ceases the mixture is warmed at 40C. for 9s hourwhere further evolution of hydrogen gas occurs and the reaction mixturedarkens. The reaction mixture is finally digested on a steam bath for 10minutes after which it is cooled and acidified with glacial acetic acid(15 ml.). The product is then obtained by dilution of the mixture withwater followed by extraction with chloroform. The dried chloroformsolution is concentrated under reduced pressure to obtain a gummyresidue which crystallizes on trituration in methanol. The orange-yellowcrystalline product, 2-carbomethoxy-5-methoxy-8-chloro-3,4,10-trioxo-1,2,3,4,4a,9,9a,10- octahydroanthracene,(1.2 g.) melts at 196-201.5C.

EXAMPLE Xlll 2Carbomethoxy-5 -hydroxy-8-chloro-3,4,10-trioxo-1,2,3,4,4a,9,9a,IO-octahydroanthracene Dimethyl oxalate, 0.84 g., and2(2- carbomethoxyethyl )-5-hydroxy-8-chloro-4-tetralone,

2.0 g., are added to a suspension of 0.34 g. sodium hydride in 10 ml.dimethyl formamide and the mixture is heated to 70C. for 3 minutes.After cooling, the reaction mixture is treated with 10 ml. acetic acidand evaporated to dryness at reduced pressure. The residual gum istriturated with water to remove sodium acetate and chromatographed tosilicic acid in chloroform. The main effluent fraction is dried to abright yellow solid which is crystallized from chloroform-hexane toprovide 380 mg. product melting at 218-219.5C. Elemental analysis,calculated for C H O CI: C, 56.7; H, 3.); Cl, 105; found: C, 56.86; H,3.89; Cl, 10.8%.

EXAMPLE XlV Diethyl 3-(a-hydroxy-3-methoxybenzyl)adipate This product isobtained by treating 5 g. diethyl 3(3- methoxybenzoyl) adipate and 2 g.5% palladium on carbon in ethanol with 40 psi hydrogen gas at roomtemperature until one molar equivalent of hydrogen is consumed. Thereaction mixture is filtered and concentrated at reduced pressure toobtain the product.

It is further converted to diethyl 3-(a-N,N-dimethylamino-3-methoxybenzyl)adipate in the following manner:

The a-hydroxy benzyl adipate ester, 0.01 mole in 15 ml. dimethoxyethane,is added to a stirred mixture of 1.9 g. (0.01 mole) p-toluenesulfonylchloride and 2.5 ml. dry pyridine in an ice bath. When the reactionsubsides the mixture is permitted to warm to room temperature, stirredfor 3 hours, and poured into 50 ml. water.

The pH is adjusted to 5 and the resulting tosyl ester recovered byfiltration.

The tosylate (0.0025 mole) is combined with 25 m1. dimethoxyethane andadded dropwise to a stirred solution of 0.015 mole dimethylamine in 50ml. dimethoxyethane at C. After addition is complete, stirring iscontinued for an hour at 0 and the reaction mixture is then heated at 60for three hours under a Dry Ice condenser. The mixture is nextevaporated in vacuo and the residue washed with water to removedimethylammonium toluenesulfonate. The product is recovered byfiltration from the water. Substitution of monomethylamine fordimethylamine in this procedure provides the correspondinga-N-methylamino derivative.

EXAMPLE XV 2-(2-Carbomethoxyethyl)-5-methoxy-4-tetralone2-(2-Carbometh0xyethyl)-5-methoxy-8-chloro-4- tetralone (1.5 g.) iscombined with palladium-oncharcoal (0.37 g.), triethylamine (0.5 g.) andmethanol 270 ml. in a standard Parr hydrogenation bottle and subjectedto fifty pounds of hydrogen pressure. The absorption of hydrogen levelsoff at approximately one molar equivalent. The catalyst is filtered off,the solution taken to dryness, and triethylamine hydrochloride isremoved by washing with water. The residual white solids weigh 1.1 g.and melt at 63-66 C. After two recrystallizations from hexane and onefrom ether the product melts at 85-87 C.

Analysis Calcd. for CH1QO4IC, 68.68; H, 6.92%; Found: C, 68.59; H,6.98%.

EXAMPLE XVl 2-(2-Carboxyethyl )-7-hydroxy-4-tetralone3-(3-methoxybenzyl) adipic acid, 22.46 g., is heated at reflux withhydriodic acid (specific gravity 1.5) for 3 hours and the methyl iodideformed is separated. The solution is evaporated in vacuo and theresulting gum triturated with cold water to yield 14.7 g. of yellowcrystalline product. Dired and recrystallized from aqueous acetone theproduct is obtained in the form of white crystals melting at 183.5-185.5C.

Analysis Calcd. for C H O C, 66.65; H, 6.02%;

Found: C, 66.60; H, 6.02%.

The same product is obtained by refluxing a mixture of 0.5 g. of the3-(3-methoxybenzyl)adipic acid with 25 ml. 48% HBr for 18 hours, thenpouring the reaction mixture into 3 volumes of water, and filtering theresulting 0.4 g. of crystalline precipitate.

' EXAMPLE xvn 2-(2-Carbomethoxyethy])-5-methoxy-8-nitro-4- tetralone Onegram of the Example XV product is slowly added to 10 ml. of concentratedsulfuric acid containing 2 m1. of nitric acid at a temperature of 0-5 C.The solution is stirred for 15 minutes and allowed to warm to roomtemperature. The mixture is poured into ice-water mixture and extractedwith chloroform, the chloroform layer separated, dried and concentratedto obtain the product.

EXAMPLE XVlII 2-( 2-Carboxyethyl)5-hydroxy-8-amino-4-tetralone Onemolecular proportion of aniline is dissolved in 2N HCl, employing about20 ml. thereof per gram of aniline, and the solution treated with onemolecular proportion of NaNO at 0 to 10C. The benzenediazonium chloridesolution is then mixed with stirring at 0 to 20C. with an aqueoussolution of 2-(2- carboxyethyl)-5-hydroxy-4-tetralone sodium salt andsufficient sodium carbonate to neutralize the excess HCl in thediazotised aniline solution. The pH of the solution is in the range8-10. Stirring is continued at 0C. for approximately two hours afterwhich careful neutralization of the reaction mixture yields the 8-phenylazo compound. The product is collected on a filter, washed anddried.

One part by weight of 2-(2-carboxyethyl)-5-hydroxy-8-phenylazo-4-tetralone is mixed with 20 parts by weight of methanol and1/5 part by weight of 5% palladium-on-carbon catalyst is added to themixture which is then hydrogenated at 30-45 psi of hydrogen gas in aconventional shaker apparatus at 30C. until two molar equivalents ofhydrogen are taken up.

After filtration, the product is recovered by high vacuum distillationof the residue obtained by removal of the solvent in vacuo. Care must beexercised to protect the amino phenol from air. It can be stabilized byacetylation, as follows:

The crude amine is placed in 20 parts water containing one molarequivalent of HCl, and 2.2 molar equivalents of acetic anhydride areadded. Sufficient sodium acetate is then added to neutralize the HCl andthe solution is warmed to 50C. After minutes the mixture is cooled andthe crude acetate separated by filtration. The solid is then dissolvedin cold 5% sodium carbonate solution and reprecipiated with 5% HCl. The2-(2- carboxyethyl)-5-hydroxy-8-N-acetylamino-4-tetralone obtained inthis manner is a preferred form of the amino compound for furtherreaction sequences.

EXAMPLE XIX 3-(2-Amino-5-hydroxybenzyl)adipic acid The procedure ofExample XVIII is repeated using 3-(3-hydroxybenzyl) adipic acid asstarting compound to obtain this product. It may be converted to theproduct of Example XVIII by the ring closure procedure of Example VI.

EXAMPLE XX 3-(2-Chloro-5hydroxybenzyl)adipic acid Three parts by weightof the product of Example XIX (obtained by evaporating the methanol) isprotected from air, immediately mixed with parts by weight of 10%aqueous hydrochloric acid at 0 C., and diazotized by gradual addition of20% aqueous sodium nitrile solution. Addition of sodium nitrite iscontinued until a positive starch iodide test on a few drops of thereaction mixture is obtained in the convention fashion. The resultingsolution is then added to parts of a boiling 10% solution of cuprouschloride in aqueous hydrochloric acid. The mixture is boiled for 10minutes and allowed to cool. The product separates from the cooledmixture and is collected in the conventional manner.

This procedure is used for the preparation of 3-(2-substituted-5-hydroxy-benzy1).adipic acid compounds such as 2-bromo(using Cu Br and HBr), 2-iodo (using KI and H 80 and 2-fluoro compounds(decomposing the dry diazonium fluoborate salt by careful heating).

EXAM PLE XXI 3 -[a -Hydroxy-a-(2-chloro 5-methoxyphenyl)ethyl- ]adipicacid diethyl ester To a solution of 3-(2-chloro-5-methoxybenzoyl-)adipic acid diethyl ester in dimethoxyethane is added dimethoxyethanesolution containing a molar equivalent'of methyl magnesium bromide.After standing for 30 minutes, the reaction mixture is acidifiedcautiously with ice and aqueous 6N HCl, and extracted with methylenechloride. The extracts are combined, washed with water, dilute aqueoussodium bicarbonate and water, dried and concentrated under reducedpressure to obtain the product.

EXAMPLE XXII 3-[a-(2-Chloro-5-methoxyphenyl)ethyl]adipic acid diethylester The product of Example XXI, 2 g., is dissolved in 150 ml. ofglacial acetic acid and hydrogenated at a pressure of 40 psi of hydrogengas for 24 hour at room temperature in the presence of 2g. of 5%palladium-incarbon catalyst. The mixture is filtered and thenconcentrated. The product is obtained. by vacuum distillation of theresidue.

EXAMPLE XXIII 3,3,4-Trimethoxybenzophenone A mixture of 40 g. of 3methoxybenzoyl chloride, 32 g. of verstrole and 250 ml. of carbondisulfide in a 3 neck round bottom flask fitted with reflux and stirreris cooled to 0C. Then 40 g. of aluminum chloride is added portionwise tothe cooled mixture and the mixture stirred for 45 minutes, after whichit is allowed to warm to room temperature. A vigorous reaction ensueswith the separation ofa yellow precipitate. The mixture is carefullywarmed on a steam bath and stirred for l 7% hours. Water is then addedto the cooled mixture and the carbon disulfide is steam distilled off.The resultant mixture is then extracted with chloroform and thechloroform layer separated, washed with dilute hydrochloric acid,followed by dilute sodium hydroxide and then dried and concentratedunder reduced pressure. The residual oil is distilled to obtain theproduct, b.p. 216- 218C. at 1.5 mm. mercury. A yield of product isobtained. The viscous product is stirred in absolute methanol andcrystallizes, m. 86C.

EXAMPLE XXIV 3 ,3 ',4-Trimethoxydiphenylmethane METHOD A A solution of 5g. of 3,3',4-trimethoxybenzophenone in 200 ml. of ethanol containing Ig. of copper chromium oxide is hydrogenated at 180C. and atmospheres ofhydrogen gas for 1.5 hours. The resultant solution is filtered andconcentrated under reduced pressure. The residual oil is distilled toobtain the product b.p. 192-194C. at 2.5 mm. mercury. The productcrystallizes on standing, the melting point of the crystals being 4546C.Elemental analysis gives the following results:

Calcd. for C H O C, 74.39; H, 7.02;

Found: C, 74.50; H, 7.18.

METHOD B This product is also obtained by hydrogenation of the startingcompound of Method A using 10% palladium on carbon in ethanol at 50C.and 40 psi of hydrogen gas. The hydrogenation procedure is also carriedout at room temperature, although the uptake of hydrogen is considerablyslower than at 50C. The product is obtained by filtration andconcentration of the hydrogenation mixture.

EXAMPLE XXV 3 ,3 '4-Trihydroxydiphenylmethane Two grams of3,3'4-trimethoxydiphenylmethane are dissolved in 10 ml. of acetic acidand 10 ml. of 48% hydrobromic acid and the mixture refluxed for 5 hours.The reaction mixture is concentrated under reduced pressure to obtain aresidual gum which is vacuumdistilled (b.p. 230C. at 0.5 mm. ofmercury). The distillate, a colorless gum, crystallizes. A 62% yield ofproduct is obtained, m. 103.5-l04C.

EXAMPLE XXVI A mixture of 3.5 g. of 3,3'4-trihydroxydiphenylmethane in50 ml. of acetone and 50 ml. of 10% aqueous sodium hydroxide is cooledto 0C. Thirty ml. of 35% aqueous hydrogen peroxide solution is thenadded dropwise, the mixture turning pale pink after 5 to 10 minutes. Anexothermic reaction occurs with considerable boiling and foaming. Themixture is allowed to stand for 1 hour and is then extracted with ethylacetate, the extract being discarded. The aqueous solution is thenacidified and extracted with ethyl acetate. Concentration of the ethanolacetate extract after drying gives the product as a gummy residue.

EXAMPLE XXVlI 3-(3-Hydroxybenzyl)adipic acid The product of thepreceding example (105 mg.) is dissolved in 13 ml. of ethanol containing1 drop of concentrated hydrochloric acid and hydrogenated over platinumoxide at 1 atmosphere of hydrogen gas at room temperature. The hydrogenuptake is exactly molecular equivalent. Filtration and concentration ofreaction mixture gives the product.

EXAMPLE XXVIIl 3-(3-Methoxybenzyl)adipic acid dimethyl ester The acidproduct of the preceding example is dissolved in aqueous sodiumhydroxide (4 molar equivalents) and agitated with 3 molar equivalents ofdimethyl sulfate at 40C. for 6 hours. The resultant solution is thendiluted with water and extracted with chloroform. The chloroform layeris separated, dried and concentrated under reduced pressure to yield anoil, b.p. 205 to 210 C. at 0.2 mm. mercury. This product is alsoobtained by treatment of the starting compound with diazomethane indiethyl ether.

In a similar manner the corresponding ethyl and propyl esters areprepared.

EXAMPLE XXIX S-(B-Methoxybenzyl)hexa-2,4-dienedioic acid Five grams of3,3'4-trimethoxydiphenylmethane are dissolved in 50 ml. of acetic acidcontaining about 10 drops of water and ozonized air containing about 4%O is then passed into the mixture for 1.5 hours (total of about 6 molesof ozone). The resultant yellow solution is poured into 1 liter of waterand extracted with chloroform. The chloroform layer is separated, washedwith aqueous sodium bicarbonate solution and concentrated under reducedpressure. The residue is dissolved in ethanol containing 2 g. of KOH andthe mixture allowed to stand at room temperature for 2 days after whichit is diluted with water and extracted with chloroform. After separationof the chloroform layer the aqueous alkaline solution is acidified withdilute hydrochloric acid and extracted with chloroform. Concentration ofthe chloroform extract gives the acid product.

The methyl, ethyl and propyl diesters of this acid are prepared byrefluxing the acid for 3 days in ethylene dichloride containing theappropriate alcohol and sulfuric acid.

EXAMPLE XXX 3-(3-Methoxybenzyl)adipic acid dimethyl ester The ester ofthe preceding example is hydrogenated in ethanol over 10% palladium oncarbon at l atmosphere of hydrogen gas at room temperature. Thetheoretical uptake of hydrogen gas (2 molar equivalents) is very rapid.The product is obtained by filtration and concentration of thehydrogenation mixture.

In similar fashion the corresponding free acid is obtained byhydrogenation of the free acid of the preceding example.

EXAMPLE XXXI The following monoester compounds are prepared by reductionof corresponding benzoyl diesters according to the methods of Example I.The free adipic acid derivatives are prepared by the methods of Examplell from the corresponding benzoyl adipic acids. The products aresubsequently converted to the corresponding diesters by conventionalprocedures, e.g. Example ll. Method B.

3-benzyladipic acid monoethyl ester 3-(3,4,5-trimethoxybenzyl)adipicacid monoethyl ester 3-(2,4,5-trimethoxybenzyl)adipic acid monoethylester 3-(2-ethyl-5-hydroxybenzyl)adipic acid monoethyl ester3-(2-chloro-5-methoxybenzyl)adipic acid monomethyl ester3-(Z-dimethylamino-S-methoxybenzyl)adipic acid monomethy] ester3-(2-amino-5-methoxybenzyl)adipic acid3-(2-acetamido-5-methoxybenzyl)adipic acid 3-(3-hydroxybenzyl)adipicacid monoethyl ester 3-(3-methyl-5-hydroxybenzyl)adipic acid monoethylester 3-(2,3-dimethyl-5-hydroxybenzyl)adipic acid monoethyl ester3-(2-methyl-5-hydroxybenzyl)adipic acid monoethyl ester3-(3-dimethylamino-5-hydroxybenzyl)adipic monoethyl ester3-(3,5-dimethoxybenzyl)adipic acid monoethyl ester3-(3-isopropyl-5-hydroxybenzyl)adipic acid monoethyl ester3-(2,3-diethyl-5-hydroxybenzyl)adipic acid monoethyl ester3-(5-benzyloxybenzyl)adipic acid monoethyl ester3-(2-chloro-5-benzyloxybenzyl)adipic acid monoethyl ester3(3-propionyloxybenzyl)adipic ester 3-(3-acetyloxybenzyl)adipic acidmonoethyl ester Those compounds having a benzyloxy substituent arereduced by the procedures of Methods A or C of Example lI. Of course,the procedure of Example II, Method A, results in hydrolysis of theester groups and necessitates re-esterification.

EXAMPLE XXXII acid acid monoethyl

2. The compound of claim 1 wherein each of R3 and R4 is lower alkyl; X4is -CONH2; A is hydrogen; X2 is hydroxyl; and X'' is 8-dimethylamino. 3.The compound of claim 1 wherein each of R3 and R4 is methyl; X4 is-CONH2; A is hydrogen; X2 is hydroxyl; and X'' is 8-hydroxyl.
 4. Thecompound of claim 1 wherein each of R3 and R4 is methyl; X4 is -CONH2; Ais hydrogen; X2 is hydroxyl; and X'' is 7-trifluoromethyl.
 5. Thecompound of claim 2 wherein each of R3 and R4 is methyl; X4 is -CONH2; Ais hydrogen; X2 is hydroxyl and X'' is 8-dimethylamino.
 6. A compoundselected from the group consisting of those having the formula: